1. Field of the Invention
This invention relates to a laser diode structure and, in particular, to a support mechanism for accurately focusing, collimating or diverging the beam produced by a laser diode.
2. Prior Art
The accurate focusing, collimating or diverging of the output light from a laser diode has been a problem in the use of these diodes to generate laser beams to be used for a number of purposes including printing. Typically, the output light from a laser diode is passed through a lens system which focuses, collimates or diverges the light beam. The lens system is formed in a housing. Precision threads are formed on the lens housing and the lens housing is then screwed into a second housing threaded internally to provide threads mating with those on the lens housing. The second housing is mounted in a fixed relationship to the fixed diode. The lens system is screwed into the second housing. The lens system, when rotated to adjust the focus of the beam, rotates concentrically around its optical axis. However, both sets of threads must be precision machined to ensure that the optical axis of the lens system is congruent with the axis of rotation of the lens housing. In other words, the optical axis and the axis of rotation of the lens system must coincide. This requires precision machining and accurate lens formation, both of which increase the cost of the lens system.
Another prior art structure to do this uses accurately formed sleeves. The lens system slides along notches in the sleeves parallel to the optical axis of the lens system to prevent lens rotation. Set screws lock the lens system in position. This method has limited accuracy and results in some undesirable transverse movement of the lens when the lens is locked by tightening the set screws.